Biomass is a general term to refer to all organic materials currently being used as energy sources including dedicated energy crops and trees, agricultural products and forage crops, agricultural wastes and residues, forest product wastes and wood chips, water plants, excretion of animals, industrial wastes including municipal wastes, and other renewable organic materials extracted from the above-described wastes. The biomass is a huge energy storage that keeps solar energy. If it is possible to effectively use the biomass, a current energy crisis caused by overuse of fossil fuels can be solved easily. Since the biomass is cultured to produce energy to be used as much as needed, it is possible to prevent excessive accumulation of carbon dioxide in the air. Therefore, it may be possible to solve global warming being currently brought up as a very serious problem.
Bioethanol as one of alternative energy sources using the biomass is extracted from plants such as sugar cane, corn, and the like and can be used as an automotive fuel in a combined manner with gasoline or solely. Therefore, the bioethanol has drawn attention as a representative renewable energy source together with biodiesel. Biomass ethanol is described in documents as follows: DiPardo, Journal of Outlook for Biomass Ethanol Production and Demand (EIA Forecasts), 2002; Sheehan, Biotechnology Progress, 15 8179, 1999; Martin, Enzyme Microbes Technology, 31 274, 2002; Greer, BioCycle, 61-65, April 2005; Lynd, Microbiology and Molecular Biology Reviews, 66 3, 506-577, 2002; and Lynd et al in “Consolidated Bioprocessing of Cellilosic Biomass: An Update,” Current Opinion in Biotechnology, 16 577-583, 2005.
However, as the bioethanol has drawn attention as alternative energy, a demand for corn, sugar crane, and wheat as sources of the bioethanol has been sharply increased, which becomes a factor of a sharp rise in crop prices. Accordingly, a method of obtaining bioethanol from crops causes the above-mentioned problem of a sharp rise in crop prices and cannot avoid criticism that such crops should be supplied to many starving people as food. Therefore, a global bioethanol market has turned its attention from crops to wood. However, there is no way of making a breakthrough since the wood needs to go through a complicated process of removing lignin or the like.
Accordingly, recently, marine algae have drawn attention as a source of the bioethanol. Since the marine algae have a high growth rate, it is possible to mass-produce them without any fertilizer or agricultural water. Further, since the marine algae are rich in various sugar components and alginic acid, they are suitable to be converted into energy. Furthermore, the marine algae are about 1.5 to 2 times richer in carbohydrates than wood.
Moreover, since the marine algae have a less dense structure than lignin, as compared with conventional biomass, it is relatively easy to perform saccharification on the marine algae, resulting in a great amount of output. Besides, since relatively abundant marine resources can be utilized, the marine algae have great potential.